In an auto analyzer used in, for example, clinical tests, a dispensing apparatus that can dispense a reagent with respect to a specimen to generate a chemical-reaction fluid of the specimen and the reagent is conventionally used. For example, in a multi-allergen test used to identify an allergy of a patient, when the dispensing apparatus dispenses a reagent (a biotinylated allergen) with respect to a specimen (blood) from a patient, a chemical-reaction fluid including a material (a specific IgE antibody conjugate) used for auto analysis can be generated.
Among such dispensing apparatuses, as shown in later-explained FIG. 18, is a dispensing apparatus that draws, by a dispensing nozzle provided at a distal end of a dispensing arm capable of rotating, a reagent from a reagent container held on a reagent table, rotates the dispensing arm driven by a stepping motor to move the dispensing nozzle onto a carriage table, and discharges the reagent into a specimen container held on the carriage table, thereby dispensing the reagent with respect to the specimen (see, e.g., Patent Document 1).
FIG. 18 is a perspective view of an appearance of a conventional dispensing apparatus 1800 utilizing the conventional technology. The conventional dispensing apparatus 1800 is an apparatus that discharges a reagent 1852 drawn from a reagent container 1851 arranged in a reagent table 1850 into a specimen container 1861 that is arranged in a specimen table 1860 and holds a specimen 1862. This dispensing apparatus 1800 includes a case 1801, a dispensing arm 1810, a driving motor 1820, a driving transmission unit 1830, and a drawing/discharging unit 1840.
The dispensing arm 1810 and the driving transmission unit 1830 are provided on an upper portion of the case 1801, and the driving motor 1820 is enclosed in the case. The dispensing arm 1810 includes a dispensing arm shaft 1811 and an arm 1812 and rotates driven by the driving motor 1820.
The dispensing arm shaft 1811 has a rotatable, rod-like shape and is assembled on an upper portion of the case 1801. The dispensing arm shaft 1811 axially supports the arm 1812 and rotates together with the arm 1812 driven by the driving motor 1820. The dispensing arm shaft 1811 moves up and down by a driving mechanism (e.g., a motor or a hydraulic cylinder) controlled by a non-depicted computer.
The arm 1812 has a rod-like shape that is pivotally supported by the dispensing arm shaft 1811 and rotates together with the dispensing arm shaft 1811, and a dispensing nozzle 1843 is held at a distal end of the arm 1812. When the arm 1812 rotates together with the dispensing arm shaft 1811 driven by the driving motor 1820, the dispensing nozzle 1843 held at the distal end of the arm 1812 can be reciprocated between a predetermined drawing position and a predetermined discharge position.
When the arm 1812 moves up and down together with the dispensing arm shaft 1811 by a driving mechanism controlled by the non-depicted computer, the dispensing nozzle 1843 held at the distal end of the arm 1812 can be moved up and down. For example, when the dispensing nozzle 1843 is positioned at the predetermined drawing position (immediately above the reagent container 1851) to draw the reagent 1852 from the reagent container 1851 arranged in the reagent table 1850, moving the arm 1812 down together with the dispensing arm shaft 1811 enables insertion of a distal end of the dispensing nozzle 1843 into the reagent 1852 in the reagent container 1851.
The driving motor 1820 is a stepping motor driven under the control of the non-depicted computer to rotate the dispensing arm 1810 through the driving transmission unit 1830. The driving transmission unit 1830 includes a drive shaft, a driving pulley, and a driving belt, and transmits driving force of the driving motor 1820 to the dispensing arm 1810.
The drawing/discharging unit 1840 includes a syringe pump unit 1841, a syringe pump pipe 1842, and a dispensing nozzle 1843. The syringe pump unit 1841 generates a pressure (a negative pressure) that is used to draw the reagent 1852 and a pressure (a positive pressure) that is used to discharge the reagent 1852 under the control of the non-depicted computer.
The pressures (the negative pressure and the positive pressure) generated by the syringe pump unit 1841 are transmitted to the dispensing nozzle 1843 through the syringe pump pipe 1842, and for example, the generation of a pressure (the negative pressure) by the syringe pump unit 1841 when the distal end of the dispensing nozzle 1843 is inserted in the reagent 1852 in the reagent container 1851 enables drawing the reagent 1852 in the reagent container 1851 from the distal end of the dispensing nozzle 1843.
On the contrary, the generation of a pressure (a positive pressure) by the syringe pump unit 1841 when the distal end of the dispensing nozzle 1843 having the reagent 1852 sucked therein is inserted in the specimen container 1861 enables discharge of the reagent 1852 with respect to the specimen container 1861 from the distal end of the dispensing nozzle 1843.    Patent Document 1: Japanese patent Application Laid-open No. 2002-311036